1. Field of the Invention
The present invention relates to a signal processing apparatus, a recording medium, and a signal processing method which can be applied to, for example, an optical disk apparatus for recording audio signals in an optical disk, the optical disk, and an optical disk apparatus for reproducing data from the optical disk. The present invention embeds input data in coefficient data, which is obtained by subjecting input signals to orthogonal transform processing, and performs inverse orthogonal transform processing on the result, thus making it possible to prevent the quality of input signals from deteriorating and to superimpose copyright data or the like in such a manner that it will be difficult to be analyzed.
2. Description of the Related Art
Hitherto, a method has been proposed whereby to protect copyrights by the so-called watermarks in recording media such as optical disks. According to this method, modulated signals or the like of data regarding copyrights that are sufficiently low so as not to affect reproduction of audio signals or the like are superimposed on the audio signals or the like.
Superimposing data related to copyrights as set forth above, however, inevitably deteriorates the quality of audio signals or the like accordingly. Especially in the case of audio signals, the deterioration in quality caused by superimposing such a type of data is worse than in the case of video signals.
There has been proposed another method whereby data related to copyright is superimposed by operating PCM audio data directly using this type of data. This method, however, is disadvantageous in that the data is relatively easily analyzed.
Due to the shortcomings described above, this type of watermarks has been unsatisfactory in practical use for protecting copyrights.
Accordingly, the present invention has been made with a view toward solving the difficulties described above, and it is an object thereof to propose a signal processing apparatus and a signal processing method that make it possible to prevent the quality of input signals from deteriorating and to superimpose copyright data or the like in such a manner that it will be difficult to be analyzed. Another object of the invention is to propose a recording medium wherein input signals processed by the foregoing signal processing apparatus and method have been recorded.
To these ends, according to one aspect of the present invention, there are provided a signal processing apparatus and a signal processing method wherein input signals undergo orthogonal transform processing to generate coefficient data, and input data is embedded in the coefficient data which is then subjected to inverse orthogonal transform processing before it is output.
According to another aspect of the present invention, there is provided a recording medium wherein input signals are recorded. The input signals are subjected to orthogonal transform processing to generate coefficient data, and input data is embedded in the coefficient data and subjected to inverse orthogonal transform processing so as to convert it back into the original input signals, which are then recorded in the recording medium.
Furthermore, in the signal processing apparatus and the signal processing method, input signals undergo orthogonal transform processing to generate coefficient data, and data embedded in the input signals is reproduced from the coefficient data.
In the signal processing apparatus and the signal processing method, input signals undergo orthogonal transform processing to generate coefficient data, and input data is embedded in the coefficient data and subjected to inverse orthogonal transform processing. This enables deterioration in quality to be hardly recognizable in comparison with a case where input data is embedded directly in input signals, and also permits input data to be embedded such that it will be difficult to find.
By recording the input signals that have been processed as set forth above in a recording medium, it is possible to record, for example, audio signals with controlled deterioration in sound quality and in such a fashion that copyright data or the like is difficult to find.
Furthermore, in the signal processing apparatus and the signal processing method, input signals undergo orthogonal transform processing to generate coefficient data, and data embedded in the input signals is reproduced from the coefficient data. This enables the data embedded in the input signals to be detected.